I will be measuring the voltage output of the A1360 using the MSP430's internal ADC in order to evaluate the current flowing through a cable - the A1360 slots into a ring concentrator that encircles a cable that will be carrying several 100s of amps.

I'm not sure what the maximum output of the A1360 will be at this stage as I'm not sure what the ring concentrator looks like yet, so I need to assume that I may have to read the full 5V output.

I'm only making a handful of these and they will be individually calibrated.

"open-drain" is a term I've heard alot since I've been working with embedded CPUs, but I've never fully understood the meaning of it. I'm just about to pull out Horrowitz and Hill to see if it can enlighten me!

In the meantime, the data sheet shows an internal functional block diagram which shows two series op-amps on the output. It also describes "output source current 3mA" and "output sink current 10mA" in the absolute max ratings section.

Does this make sense in terms of working out whether its open-drain or not?

" The predecessor of three-stage logic was 'open-collector' logic, which allows you to share a single line among the outputs of several drivers. An open-collector (or open-drain) output simply omits the active pullup transistor of the output stage. The name 'open-collector' is a good one. When you use such gates you must supply and external pullup resistor somewhere. "

Hmmm, not sure I'm any clearer after that (imagines the many experts on this forum rolling their eyes..............)

Sorry Stube40 I could have been more descriptive with that term. Yes I meant "open drain" as an output that can pull low to connect to ground, but will not output a positive (source) voltage. Normally you can consider "open drain output" sensors as the equivalent of a simple switch to ground.

The Allegro page shows the internals of the A1360 and it appears to be a linear voltage output, so that is not open-drain, sorry for the confusion;

Does the datasheet list the max output voltage of the sensor? Is there a spec for Vout?

Or (as Jaclement suggested) you could just run the sensro from 3.3v like your micro, but check the datasheet to see that the sensor will operate properly at 3.3v.

I've manged to establish that the magnetic fields I will be measuring equate to a maximum of around 280mV from the sensors output, whilst expecting normal usage to be in the 0 to 59mV range.

Also, since I will be needing to measure both mag field polarities, I need to make it bi-directional. The sensor comes setup with a DC offset of 2.0V, so this would mean that 2.280V equates to my maximum positive mag field measurement and 1.720V is the max negative field.

So, I'm not thinking I will need a to put together a circuit with at least one opamp (possibly two??) to get this working. Best dust off my copy of Horrowitz and Hill and see what I can come up with.............